Method for preventing, treating, or ameliorating a microbial infection

ABSTRACT

A method for preventing, treating, or ameliorating a microbial infection can include administering thymoquinone or a pharmaceutical composition comprising thymoquinone to a patient in need thereof. The patient may be suffering from a microbial infection caused by gram-negative bacteria, gram-positive bacteria, or fungi. The microbial infection may be caused by gram negative bacteria. The gram-negative bacteria may include Acinetobacter baumannii. The gram-negative bacteria may include Pseudomonas aeruginosa. The microbial infection may be caused by antimicrobial sensitive Acinetobacter baumannii or antimicrobial resistant Acinetobacter baumannii.

BACKGROUND 1. Field

The disclosure of the present patent application relates to antimicrobial agents, and particularly to a thymoquinone antimicrobial agent and its use against drug-susceptible and drug-resistant microbial infections.

2. Description of the Related Art

Pathogenic microorganisms such as bacteria and fungi cause infections in humans and animals. Sometimes it is difficult to treat these infections using available antimicrobial agents. In particular, the treatment of life-threatening infections caused by resistant pathogenic microorganisms is a challenging task. In drug resistant cases, pathogenic microorganisms have reduced or lost their susceptibility to one or more antimicrobial agents. Antimicrobial resistance reduces the efficacy of antimicrobial drugs or renders the drug(s) ineffective against targeted microbe(s) at a standard dose. Treatment of infections caused by resistant microbes is difficult, complicated and expensive. In such cases, patients' suffering is prolonged and chances of mortality are increased. Multidrug resistance limits the therapeutic options available for treatment of infections and forces healthcare providers to use comparatively higher doses or more toxic and/or expensive antimicrobial agents.

Gram-negative infections are typically due to common pathogens such as Acinetobacter, Pseudomonas aeruginosa, and the Enterobacteriaceae family. Acinetobacter baumannii infections are typically hospital-derived infections.

Thus, a method for treating microbial infections solving the aforementioned problems is desired.

SUMMARY

A method for preventing, treating, or ameliorating a microbial infection can include administering thymoquinone or a pharmaceutical composition comprising thymoquinone to a patient in need thereof. The microbial infection may be caused by gram-negative bacteria, gram-positive bacteria, or fungi. The gram-negative bacteria may include Acinetobacter baumannii. The gram-negative bacteria may include Pseudomonas aeruginosa. The microbial infection may be caused by antimicrobial sensitive Acinetobacter baumannii or antimicrobial resistant Acinetobacter baumannii. The pharmaceutical composition may be formulated as a micro-emulsion.

These and other features of the present disclosure will become readily apparent upon further review of the following specification and drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method for preventing, treating, or ameliorating a microbial infection can include administering thymoquinone or a pharmaceutical composition comprising thymoquinone to a patient in need thereof. The patient may include a human or an animal. The microbial infection may be caused by gram-negative bacteria, gram-positive bacteria, or fungi. The microbial infection may be caused by gram negative bacteria. The gram-negative bacteria may include Acinetobacter baumannii. The gram-negative bacteria may include Pseudomonas aeruginosa. The microbial infection may be caused by antimicrobial sensitive Acinetobacter baumannii or antimicrobial resistant Acinetobacter baumannii.

As used herein, the term “about” when modifying a numerical value shall mean within 10% of the modified numerical value.

Thymoquinone (2-isopropyl-5-methylbenzo-1, 4-quinone) is a bioactive molecule. Thymoquinone has been reported to have anti-oxidant activity, anti-inflammatory activity, and anti-cancer activity. Thymoquinone has also demonstrated protective effects on several organs against oxidative damage.

A pharmaceutical composition comprising thymoquinone can include thymoquinone and at least one pharmaceutically acceptable excipients. Pharmaceutically acceptable excipients can be selected from carriers, diluents, stabilizers, complexing agents, buffers, binders, emulsifiers, surfactants, solubilizers, thickeners, suspending agents, hydrophobic ointment base, gel forming polymers, lubricants, colors, flavors, and preservatives. In an embodiment, the pharmaceutical composition comprising thymoquinone is formulated as a microemulsion including thymoquinone, an oil, a surfactant, and water. In an embodiment, the pharmaceutical composition includes from about 0.01% to about 1.0% w/v thymoquinone, from about 2% to about 6% by volume oil, from about 25% to about 40% by volume surfactant, and a remainder of the pharmaceutical composition includes water.

The pharmaceutical composition may include at least one supplementary antimicrobial agent. The thymoquinone and the at least one supplemental antimicrobial agent can be in intimate contact in the pharmaceutical composition. The thymoquinone and the at least one supplemental antimicrobial agent in the pharmaceutical composition may be separated by a barrier. The thymoquinone and the at least one additional supplemental antimicrobial agent can be separately formulated, but simultaneously used.

The supplemental antimicrobial agent can include at least one of the following: aminoglycosides (Amikacin, Gentamicin, Kanamycin, Neomycin, Netilmicin, Tobramycin, Paromomycin, Streptomycin), Ansamycins (Geldanamycin, Rifaximin), Carbapenems (Ertapenem, Doripenem, Imipenem/Cilastatin, Meropenem), Cephalosporins (Cefadroxil, Cefazolin, Cefalexin, Cefaclor, Cefprozil, Cefuroxime, Cefixime, Cefdinir, Cefditoren, Cefoperazone, Cefotaxime, Cefpodoxime, Ceftazidime, Ceftibuten, Ceftriaxone, Cefepime, Ceftaroline fosamil, Ceftobiprole) Glycopeptides (Teicoplanin, Vancomycin, Telavancin, Dalbavancin, Oritavancin) Lincosamides (Clindamycin, Lincomycin) Lipopeptide (Daptomycin) Macrolides (Azithromycin, Clarithromycin, Erythromycin, Roxithromycin, Telithromycin, Spiramycin) Monobactams (Aztreonam) Nitrofurans (Furazolidone, Nitrofurantoin) Oxazolidinones (Linezolid, Posizolid, Radezolid, Torezolid) Penicillins (Amoxicillin, Ampicillin, Azlocillin, Dicloxacillin, Flucloxacillin, Mezlocillin, Methicillin, Nafcillin, Oxacillin, Piperacillin) Penicillin combinations (Amoxicillin/clavulanate, Ampicillin/sulbactam, Piperacillin/tazobactam, Ticarcillin/clavulanate) Polypeptides (Bacitracin, Colistin, Polymyxin B) Quinolones/Fluoroquinolones (Ciprofloxacin, Enoxacin, Gatifloxacin, Gemifloxacin, Levofloxacin, Lomefloxacin, Moxifloxacin, Nadifloxacin, Nalidixic acid, Norfloxacin, Ofloxacin, Trovafloxacin, Grepafloxacin, Sparfloxacin, Temafloxacin) Sulfonamides (Mafenide, Sulfacetamide, Sulfadiazine, Silver sulfadiazine, Sulfadimethoxine, Sulfamethizole, Sulfamethoxazole, Sulfanilimide, Sulfasalazine, Sulfisoxazole, Co-trimoxazole, Sulfonamidochrysoidine) Tetracyclines (Demeclocycline, Doxycycline, Metacycline, Minocycline, Oxytetracycline, Tetracycline) Anti-mycobacterials (Capreomycin, Cycloserine, Ethambutol, Ethionamide, Isoniazid, Pyrazinamide, Rifampicin, Rifabutin, Rifapentine, Streptomycin) other antibiotics (Arsphenamine, Chloramphenicol, Fosfomycin, Fusidic acid, Metronidazole, Mupirocin, Thiamphenicol, Tigecycline), essential oils and their active constituents (Clove oil, Eugenol, Cinnamaldehyde), and myrrh (Commiphora myrrha) and its active ingredients.

The methods described herein may be used to prevent, treat, or ameliorate microbial infections caused by gram-positive bacteria, gram negative bacteria, or fungi. The methods may be used to prevent, treat, or ameliorate antimicrobial sensitive as well as antimicrobial resistant microorganisms.

The pathogenic gram-positive bacteria may include Staphylococcus (e.g., S. epidermis and S. aureus); Corynebacterium (e.g., C. pyogenes and C. pseudotuberculosis); Micrococcus; Streptococcus (e.g., S. pyogenes, S. equis, S. zooepidemicus, S. equisimilis, S. pneumoniae and S. agalactiae); Erysipelothrix (e.g, E. rhusiopathiae); Bacillus (e.g., B. anthracis); Listeria (e.g., L. monocytogenes); Clostridium (C. perfringens); and Mycobacterium (M. tuberculosis and M. leprae). Animal or human subjects infected with these pathogens may be detected by established methods.

The pathogenic gram negative bacteria infection may include Enterobacteriaceae (Escherichia, e.g., E. coli; Citrobacter; Enterobacter; Shigella; Salmonella; Edwardsiella; Hafnia; Klebsiella, e.g., K. pneumoniae; Morganella; Proteus; Providencia; Serratia; Yersinia); Pseudomonadaceae (Pseudomonas, especially P. aeruginosa, Burkholderia, Stenotrophomonas, Shewanella, Sphingomonas, Comamonas), Neisseria, Moraxella, Vibrio, Aeromonas, Brucella, Francisella, Bordetella, Legionella, Bartonella, Coxiella, Haemophilus, Pasteurella, Mannheimia, Actinobacillus, Gardnerella, Spirochaetaceae (Treponema and Borrelia), Bacteroidaceae (Bacteroides, Fusobacterium, Prevotella, Porphyromonas), Leptospiraceae, Campylobacter, Helicobacter, Spirillum, Streptobacillus, Acinetobacter, especially Acinetobacter baumanii. Animal or human subjects infected with these pathogens may be detected by established methods.

The pathogenic fungi may include Candida (e.g., C. albicans); Malassezia (e.g., M. dermatis); Coccidioides (e.g., C. immitis); Penicillium (e.g., P. marneffei); and Pneumocystis (e.g., P. carinii); Hyphomyces (e.g., H. destruens); Cryptococcus (e.g., C. neoformans); Aspergillus (e.g., A. fumigatus); Histoplasma (e.g., H. capsulatum); Blastomyces (e.g., B. dermatiditis); Rhinosporidium; Sporothrix; and dermatophytes. Animal or human subjects infected with these pathogens may be detected by established methods.

In an embodiment the pharmaceutical composition may be administered to a human or animal patient in a suitable form. A suitable form for topical administration (skin and mucous membrane) may include a topical ointment, cream, micro-emulsion, nano-emulsion, spray, lotion, oil, powder, liniment, solution, or a gel. A suitable form for oral administration may include a tablet, capsule, pellet, granules, solution, lozenge, suspensions, emulsions, micro-emulsion, or a nano-emulsion. The pharmaceutical composition can also be formulated as injectable solution, powder ready for reconstitution for injection, inhalant, or a suppository.

In an embodiment, the pharmaceutical composition may be formulated as a microemulsion. The microemulsion can include thymoquinone, an oil, at least one of a surfactant and a co-surfactant, and water. The oil can be selected from fixed oils and essential oils.

In an embodiment the thymoquinone antimicrobial agent may be protected from light and packaged in suitable light resistant container. The thymoquinone antimicrobial agent may be packaged in aluminum tubes, light resistant plastic tubes, light resistant bottles or jar like containers, or in light resistant blister packaging.

In an embodiment, the pharmaceutical composition may be delivered topically to the patient via a dressing comprising thymoquinone. The dressing may also comprise an additional antimicrobial agent along with thymoquinone. Suitable dressings may include bandages, gauzes, tissues, films, gels, or foams.

In an embodiment, the pharmaceutical composition may be provided for systemic use. For systemic use, the pharmaceutical composition can be administered orally, parenterally (intravenous, intramuscular, or subcutaneous injections), or by the nasal route (through solution or inhalator or spray).

In an embodiment, the pharmaceutical composition may be provided for topical use. For topical use, the pharmaceutical composition may be administered on the skin or on a mucous membrane (e.g., buccal mucosa, eyes and ears, rectal mucosa, vaginal mucosa) of the patient.

For prevention, treatment or amelioration of infection, the thymoquinone antimicrobial agent may be administered or applied at an appropriate frequency. The thymoquinone antimicrobial agent may be administered or applied at least once a day, twice a day, or thrice a day. The thymoquinone antimicrobial agent may be administered or applied at an appropriate frequency for at least 3 days.

For systemic or topical treatment of infection, the amount of thymoquinone administered will depend on multiple factors including age and weight of the subject, severity and size of the wound, the numbers and types of additional active antimicrobial agents contained in the composition administered, and the ratio of active antimicrobial agents in the composition.

The thymoquinone antimicrobial agent may be administered upon detecting emerging antibiotic resistance.

The thymoquinone antimicrobial agent may be used for the treatment of skin infections, such as burn and wound infections, especially those caused by Acinetobacter baumannii.

The thymoquinone antimicrobial agent may be used for the treatment of infections in animals. These animal infections may include skin infections, such as burn and wound infections, especially those caused by Acinetobacter baumannii.

The following examples illustrate the present teachings:

EXAMPLES Example 1 Method of Making a Micro-Emulsion Composition with Thymoquinone and Clove Oil (Microemulsion 1)

A pharmaceutical composition was prepared including thymoquinone (0.1% w/v), Clove Oil (3% v/v), Tween-20 (30% v/v) and Water (q.s. up to 100%). Briefly, thymoquinone was dissolved in clove oil to form a first mixture and then tween-20 was added to form a second mixture. The second mixture was vortexed for 1 to 2 minutes and then sonicated for 2-3 minutes in a bath sonicator. After sonication, water was added dropwise to the second mixture, while continuously vortexing to provide a microemulsion. The resulting pharmaceutical composition comprising a micro-emulsion of thymoquinone, clove oil, tween-20 and water was further sonicated to remove air bubbles.

Example 2 Method of Making a Control Micro-Emulsion Composition with Clove Oil (Microemulsion 2)

A pharmaceutical composition was prepared containing clove Oil (3% v/v), Tween-20 (30% v/v), and water (q.s. up to 100%). Briefly, clove oil and tween 20 were mixed together to form a mixture. The mixture was vortexed for 2 to 3 minutes and then sonicated for 2-3 minutes in a bath sonicator. After sonication, water was added dropwise to the mixture, while continuously vortexing to provide a microemulsion. The resulting pharmaceutical composition comprising a micro-emulsion of clove oil, tween-20 and water was further sonicated to remove air bubbles.

Example 3 Determination of Antimicrobial Susceptibility (Acinetobacter baumanii Strains)

A total of 33 non-duplicate, non-consecutive clinical isolates of Multi-Drug Resistant (MDR) Acinetobacter baumannii were collected from burn wards (“ABI-AB33”). Acinetobacter baumannii ATCC BAA 747 and Pseudomonas aeruginosa ATCC 27853 were used as control strains. The isolates were stored at −80° C. in trypticase soy broth containing 20% glycerol.

Antimicrobial susceptibility tests of the collection of isolates were conducted using the disc diffusion method. The experiment was performed according to the recommendations and guidelines of Clinical Laboratory Standard Institutes (CLSI M100-S24; 2014). Clinical and Laboratory Standards Institute (CLSI), “Performance standards for antimicrobial susceptibility testing; twenty-fourth informational supplement,” Document M100-S24, Clinical and Laboratory Standards Institute (CLSI), Wayne, Pa., USA, 2014.

A panel of commercial antibiotic discs (Amoxicillin (AMX), Amoxicillin/clavulanic acid (AMX/CLA), Piperacillin (PIP), Piperacillin/Tazobactam (PIP/TAZ), Ceftazidime (CAZ), Cefotaxime (CTX), Cefepime (FEP), Cefoxitin (FOX), Aztreonam (ATM), Imipenem (IP), Gentamicin (GEN), Amikacin (AK), Neomycin (NEO), Levofloxacin (LEV), Chloramphenicol (CHL), Tetracycline (TET), sulfamethoxazole/trimethoprim (SUL/TRI) was used for susceptibility testing. All commercial antibiotic discs were purchased from BBL (Becton Dickinson, USA).

Forty grams of Mueller-Hinton Agar (MHA) were suspended in 1 Liter distilled water and then boiled to dissolve the powder completely. The medium was sterilized by autoclaving at 121° C. for 15 min. After autoclaving, the medium was cooled to 45° C. and 25 mL of molten agar media was poured into sterile Petri dishes (90 mm diameter) to give a depth of about 4 mm. The surface of the agar was dried to remove excess moisture before use. The plates were stored at 4-8° C. in sealed plastic bags if not used immediately.

The inoculum suspension was prepared by selecting three to five morphologically similar colonies from overnight growth (16-24 h of incubation) on blood agar medium. The colonies were suspended in sterile normal saline to give the density of a McFarland 0.5 standard, which is approximately equivalent to 1-2×10⁸ CFU/mL. The suspension density was measured using a UV spectrophotometer calibrated with a 0.5 McFarland standard. The density of the suspension was adjusted to McFarland 0.5 by addition of saline or more microorganisms. The adjusted inoculum suspension was used within 60 min of preparation.

A sterile cotton swab was dipped into the bacterial suspension and the excess fluid was removed by turning the swab against the inside wall of the tube to avoid over-inoculation of plates. The inoculum was spread evenly over the entire surface of the agar plate by swabbing in three directions.

The predetermined panel of antimicrobial disks was applied firmly on the inoculated Mueller-Hinton agar surface within 15 min of inoculation of the plates by a disc dispenser device. A maximum of six disks were accommodated on a 90-mm circular plate.

Within 15 min of application of antimicrobial disks, the plates were inverted and incubated aerobically at 35-37° C. for 18-20 h.

After incubation, inhibition zones were measured at the point where no obvious growth is detected by the unaided eye when the plate is held about 30 cm from the eye. Inhibition zone diameters were measured to the nearest millimeter with a ruler. The plates were read from the back of the plate with reflected light against a dark background. Zone diameters were interpreted and categorized as susceptible “S”, intermediate “I”, or resistant “R” according to the CLSI clinical breakpoint tables (see Table 1 and Table 2). “NZ” indicated that no zone of inhibition was observed.

TABLE 1 Antibiotic Susceptibility Testing Against Acinetobacter Baumannii Isolates (Inhibition zone in mm) AMX AMX/CLA PIP PIP/TAZ CAZ CTX FEP FOX AB1 NZ R NZ R 21 S 22 S 20 S NZ R 20 S NZ R AB2 NZ R NZ R 20 I 22 S 17 I NZ R 16 I NZ R AB3 NZ R NZ R 32 S 35 S 26 S 15 I 18 S NZ R AB4 NZ R NZ R 21 S 22 S 21 S  8 R 14 R NZ R AB5 NZ R NZ R NZ R NZ R 9 R NZ R  7 R NZ R AB6 NZ R NZ R 18 I 18 I 28 S 17 I 21 S NZ R AB7 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB8 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB9 NZ R NZ R 24 S 25 S 21 S 11 R 22 S NZ R AB10 NZ R NZ R NZ R NZ R NZ R NZ R  7 R NZ R AB11 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB12 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB13 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB14 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB15 NZ R NZ R NZ R NZ R NZ R NZ R  8 R NZ R AB16 NZ R NZ R 16 R 25 S 32 S 32 S 35 S 22 S AB17 NZ R NZ R 15 R 15 R 12 R NZ R 11 R NZ R AB18 NZ R NZ R  8 R  8 R NZ R NZ R NZ R NZ R AB19 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB20 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB21 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB22 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB23 NZ R NZ R NZ R 10 R NZ R NZ R NZ R NZ R AB24 NZ R NZ R NZ R  9 R NZ R NZ R  7 R NZ R AB25 NZ R NZ R 10 R 12 R 17 I 16 I 10 R NZ R AB26 NZ R NZ R NZ R  9 R 15 I NZ R 14 R NZ R AB27 NZ R  7 R  8 R 12 R  8 R NZ R  8 R NZ R AB28  9 R  8 R  7 R  9 R  8 R NZ R NZ R NZ R AB29 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R AB30 NZ R NZ R  8 R 10 R NZ R NZ R NZ R NZ R AB31  8 R  8 R  8 R  9 R  8 R  8 R NZ R  9 R AB32  8 R  8 R  8 R 10 R  8 R  8 R NZ R NZ R AB33 NZ R NZ R 22 S 23 S 22 S 21 I 18 S NZ R Break Points Sensitive ≥17 ≥18 ≥21 ≥21 ≥18 ≥23 ≥18 ≥18 Intermediate 14-16 14-17 18-20 18-20 15-17 15-22 15-17 15-17 Resistant ≤13 ≤13 ≤17 ≤17 ≤14 ≤14 ≤14 ≤14

TABLE 2 Antibiotic Susceptibility Testing Against Acinetobacter Baumannii Isolates (Inhibition zone in mm) ATM IP GEN AK NEO TET CHL SUL/TRI LEV AB1 NZ R NZ R 24 S 24 S 23 S NZ R NZ R NZ R 30 S AB2 NZ R NZ R 20 S 20 S 20 S 22 S 24 S 23 S 30 S AB3 NZ R NZ R 24 S 26 S 22 S 22 S 26 S 23 S 29 S AB4 NZ R NZ R 22 S 21 S 27 S 21 S 23 S 20 S 30 S AB5 NZ R  8 R 15 S  7 R 10 R NZ R  8 R NZ R 19 S AB6 20 S 12 R 26 S 30 S 14 I NZ R NZ R NZ R 21 S AB7 NZ R NZ R NZ R NZ R 12 R 21 S NZ R NZ R 14 I AB8 NZ R  7 R NZ R 12 R 11 R 26 S  7 R NZ R 15 I AB9 NZ R NZ R 21 S 22 S 20 S 23 S 24 S 25 S 28 S AB10 13 R NZ R NZ R NZ R NZ R NZ R NZ R  8 R 14 I AB11 NZ R NZ R NZ R NZ R NZ R NZ R NZ R NZ R 11 R AB12 NZ R 11 R 12 R 21 S 15 S NZ R NZ R NZ R 10 R AB13 NZ R  9 R NZ R 22 S  9 R NZ R NZ R NZ R  8 R AB14 NZ R 15 R NZ R NZ R NZ R 24 S NZ R NZ R 11 R AB15 11 R NZ R 20 S 13 R 13 I 19 S 10 R NZ R 15 I AB16 33 S 34 S 18 S 19 S NZ R NZ R 30 S 26 S NZ R AB17 15 R 15 R 24 S 22 S 20 S 21 S 13 I NZ R 11 R AB18 10 R NZ R 17 S 14 R 15 S 20 S  8 R NZ R 13 R AB19  8 R NZ R 20 S 14 R 13 I 17 S  8 R NZ R 11 R AB20 NZ R 15 R NZ R NZ R NZ R 28 S NZ R NZ R 13 R AB21  7 R NZ R 17 S 11 R 13 I 19 S NZ R NZ R 14 I AB22 NZ R 15 R NZ R NZ R 7 R 20 S NZ R NZ R 14 I AB23 NZ R 20 I NZ R NZ R 10 R 23 S NZ R NZ R 11 R AB24 NZ R NZ R 19 S 14 R 14 I 19 S  8 R NZ R 12 R AB25 13 R 23 S 19 S NZ R  8 R 25 S NZ R 21 S 14 I AB26 12 R 22 S NZ R 18 S 20 S NZ R 25 S NZ R NZ R AB27 NZ R  9 R  8 R  9 R  9 R  8 R NZ R NZ R  8 R AB28 NZ R  8 R 20 S 15 I 15 S 20 S 14 I NZ R 15 I AB29 NZ R  9 R 20 S 15 I 15 S 19 S 12 R NZ R 15 I AB30  9 R  9 R 20 S 15 I 15 S 20 S 11 R NZ R 15 I AB31 NZ R  9 R  8 R NZ R  8 R NZ R  8 R NZ R 10 R AB32  8 R 18 R NZ R NZ R 10 R 28 S  9 R NZ R 18 S AB33  9 R NZ R 20 S 25 S 20 S 24 S 18 S 24 S 30 S Break Point Sensitive ≥22 ≥22 ≥15 ≥17 ≥15 ≥15 ≥18 ≥16 ≥17 Intermediate 16-21 19-21 13-14 15-16 13-14 12-14 13-17 11-15 14-16 Resistant ≤15 ≤18 ≤12 ≤14 ≤12 ≤11 ≤12 ≤10 ≤13

Example 4 Thymoquinone MIC Determination

Minimum Inhibitory Concentration (MIC) is the lowest concentration of an antimicrobial agent that prevents visible growth of a microorganism in an agar or broth dilution susceptibility test. MIC of thymoquinone was determined by the broth dilution method against 33 MDR Acinetobacter baumannii strains and standard sensitive culture collection strain of Acinetobacter baumannii and Pseudomonas aeruginosa. The MIC of gentamicin was determined by broth dilution method against six MDR Acinetobacter baumannii strains and standard sensitive culture collection strains of Acinetobacter baumannii and Pseudomonas aeruginosa. MIC testing was performed according to the recommendations and guidelines of Clinical Laboratory Standard Institutes (CLSI M07-A9; 2012). Clinical and Laboratory Standards Institute (CLSI), “Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard,” Document M07-A9, Clinical and Laboratory Standards Institute (CLSI), Wayne, Pa., USA, 2012.

Twenty-one grams of Mueller-Hinton Broth (MHB) was suspended in 1 Liter distilled water and then boiled to dissolve the powder completely. The medium was sterilized by autoclaving at 121° C. for 15 min. After autoclaving, the medium was cooled to room temperature before use or stored in the fridge until used.

Thymoquinone was weighed and dissolved in Dimethyl sulfoxide (DMSO) to produce a thymoquinone stock solution with a concentration of 5,120 μg/ml. Gentamicin sulfate was weighed and dissolved in water to produce a gentamicin sulfate stock solution with a concentration of 5,120 μg/ml, equivalent to gentamicin base.

Dilutions of thymoquinone and gentamicin sulfate stock solutions were prepared volumetrically in the MHB as follows:

One mL of original stock solution (5,120 μg/ml) was added to 9 ml sterile MHB to give the working first dilution (512 μg/mL). 12 sterile 7 mL PJ tubes were arranged in a rack in a row. Each tube contained one mL sterile MHB. Ten tubes were labeled as 128 μg/mL, 64 μg/mL, 32 μg/mL, 16 μg/mL, 8 μg/mL, 4 μg/mL, 2 μg/mL, 1 μg/mL, 0.51 μg/mL and 0.25 μg/mL. The eleventh and twelfth tubes were labeled as positive and negative control, respectively.

The working dilution (512 μg/mL) was serially diluted to give two-fold dilutions. One mL of the working dilution (512 μg/mL) was dispensed in the first tube (labeled as 128 μg/mL) to give a concentration of 256 μg drug/mL MHB. One mL of the first tube was added to the second tube (labeled as 64 μg/mL) to give a concentration of 128 μg drug/mL MHB. One mL of the second tube was transferred to the third tube (labeled as 32 μg/mL) to give a concentration of 64 μg drug/mL MHB. One mL of the third tube was added to the fourth tube (labeled as 16 μg/mL) to give a concentration of 32 μg drug/mL MHB. One mL of the fourth tube was dispensed in the fifth tube (labeled as 8 μg/mL) to give a concentration of 16 μg drug/mL MHB. One mL of the fifth tube was dispensed in the sixth tube (labeled as 4 μg/mL) to give a concentration of 8 μg drug/mL MHB. One mL of the sixth tube was added to the seventh tube (labeled as 2 μg/mL) to give a concentration of 4 μg drug/mL MHB. One mL of the seventh tube was added to the eighth tube (labeled as 1 μg/mL) to give a concentration of 2 μg drug/mL MHB. One mL of the eighth tube was transferred to the ninth tube (labeled as 0.5 μg/mL) to give a concentration of 1 μg drug/mL MHB. One mL of the ninth tube was transferred to the tenth tube (labeled as 0.25 μg/mL) to give a concentration of 0.5 μg drug/mL MHB. The contents were mixed thoroughly by pipetting up and down three times. One mL of the content of the tenth tube was discarded.

The inoculum suspensions (at 1-2×10⁸ CFU/mL) were diluted 1:100 in MHB to obtain 1×10⁶ CFU/mL. One mL of the diluted inoculum suspension (1×10⁶ CFU/mL) was transferred to each tube except tube 12. This resulted in 1:2 dilutions of each drug concentration and a 1:2 dilution of the inoculums (to 5×10⁵ CFU/mL).

All inoculated tubes were incubated for 16-20 hours at 37° C. aerobically. After this incubation period, MIC was determined manually by observing the lowest concentration of antimicrobial agent showing no visible growth (turbidity). The MIC of thymoquinone against Acinetobacter baumannii isolates and standard strain of Acinetobacter baumannii ATCC BAA 747 is presented in Table 3. The MIC of gentamicin against Acinetobacter baumannii isolates and standard strain of Acinetobacter baumannii ATCC BAA 747 is presented in Table 4. The MIC of thymoquinone and gentamicin against Pseudomonas aeruginosa ATCC 27853 was found to be 64 μg/ml and ≤2 μg/ml, respectively.

TABLE 3 MIC of Thymoquinone Against Acinetobacter baumannii Isolates (μg/ml) Isolate MIC Isolate MIC Isolate MIC Isolate MIC AB1 32 AB10 16 AB19 64 AB28 64 AB2 32 AB11 32 AB20 64 AB29 64 AB3 32 AB12 32 AB21 32 AB30 32 AB4 32 AB13 32 AB22 64 AB31 32 AB5 32 AB14 32 AB23 32 AB32 32 AB6 64 AB15 32 AB24 32 AB33 32 AB7 32 AB16 64 AB25 32 A.b. ATCC BAA 747 32 AB8 32 AB17 64 AB26 64 P a. ATCC 27853 64 AB9 32 AB18 32 AB27 64

TABLE 4 MIC of Gentamicin Sulfate Against Acinetobacter baumannii Isolates (μg/ml) Isolates MIC AB7 32 AB8 64 AB10 32 AB11 32 AB12 32 AB13 32 A. baumannii ATCC BAA 747 1 P. aeruginosa ATCC 27853 ≤2

Example 5 Determination of MIC of the Micro-Emulsion of Example 1

Nine sterile 7 mL PJ tubes were arranged in a rack in a row. Each tube contained one mL sterile MHB. Seven tubes were labeled as 7.847 mg+256 μg/mL, 3.923 mg+128 μg/mL, 1.961 mg+64 μg/mL, 0.980 mg+32 μg/mL, 0.490 mg+16 μg/mL, 0.245 mg+8 μg/mL and 0.122 mg+4 μg/mL. The eighth and ninth tubes were labeled as positive and negative controls, respectively.

The micro-emulsion made according to Example 1 was serially diluted to give two-fold dilutions as follows: one mL of the micro-emulsion of Example 1 was dispensed in the first tube (labeled as 7.847 mg+256 μg/mL) to give a concentration of 15.69 mg+512 μg drug/mL MHB. One mL of the first tube was added to the second tube (labeled as 3.923 mg+128 μg/mL) to give a concentration of 7.847 mg+256 μg drug/mL MHB. One mL of the second tube was transferred to the third tube (labeled as 1.961 mg+64 μg/mL) to give a concentration of 3.923 mg+128 drug/mL MHB. One mL of the third tube was added to the fourth tube (labeled as 0.980 mg+32 μg/mL) to give a concentration of 1.961 mg+64 drug/mL MHB. One mL of the fourth tube was dispensed in the fifth tube (labeled as 0.490 mg+16 μg/mL) to give a concentration of 0.980 mg+32 drug/mL MHB. One mL of the fifth tube was dispensed in the sixth tube (labeled as 0.245 mg+8 μg/mL) to give a concentration of 0.490 mg+16 μg drug/mL MHB. One mL of the sixth tube was added to the seventh tube (labeled as 0.122 mg+4 μg/mL) to give a concentration of 0.245 mg+8 μgdrug/mL MHB. One mL of the content of the seventh tube was discarded. Inoculum suspensions (at 1-2×10⁸ CFU/mL) were diluted 1:100 in MHB to obtain 1×10⁶ CFU/mL. One mL of the diluted inoculum suspension (1×10⁶ CFU/mL) was transferred to each tube except tube number nine. This resulted in a 1:2 dilutions of each drug concentration and a 1:2 dilution of the inoculums (5×10⁵ CFU/mL).

Another nine sterile 7 mL PJ tubes were arranged in a rack in a row. Each tube contained one mL sterile MHB. Seven tubes were labeled as 7.847 mg/mL, 3.923 mg/mL, 1.961 mg/mL, 0.980 mg/mL, 0.490 mg/mL, 0.245 mg/mL and 0.122 mg/mL. The eighth and ninth tubes were labeled as positive and negative control, respectively.

The micro-emulsion of Example 2 was serially diluted to give two-fold dilutions as follows: one mL of the micro-emulsion of Example 2 was dispensed in the first tube (labeled as 7.847 mg/mL) to give a concentration of 15.69 mg drug/mL MHB. One mL of the first tube was added to the second tube (labeled as 3.923 mg/mL) to give a concentration of 7.847 mg drug/mL MHB. One mL of the second tube was transferred to the third tube (labeled as 1.961 mg/mL) to give a concentration of 3.923 mg drug/mL MHB. One mL of the third tube was added to the fourth tube (labeled as 0.980 mg/mL) to give a concentration of 1.961 mg drug/mL MHB. One mL of the fourth tube was dispensed in the fifth tube (labeled as 0.490 mg/mL) to give a concentration of 0.980 mg drug/mL MHB. One mL of the fifth tube was dispensed in the sixth tube (labeled as 0.245 mg/mL) to give a concentration of 0.490 mg drug/mL MHB. One mL of the sixth tube was added to the seventh tube (labeled as 0.122 mg/mL) to give a concentration of 0.245 mg drug/mL MHB. One mL of the content of seventh tube was discarded. Inoculum suspensions (at 1-2×10⁸ CFU/mL) were diluted 1:100 in MHB to obtain 1×10⁶ CFU/mL. One mL of the diluted inoculum suspension (1×10⁶ CFU/mL) was transferred to each tube except tube number nine. This resulted in a 1:2 dilution of each drug concentration and a 1:2 dilution of the inoculums (to 5×10⁵ CFU/mL).

All inoculated tubes were incubated for 16-20 hours at 37° C. aerobically. After this incubation period, MIC was determined manually by observing the lowest concentration of antimicrobial agent showing no visible growth (turbidity). The MIC of the micro-emulsion of Example 1 and the micro-emulsion of Example 2 against Acinetobacter baumannii isolates is presented in Table 5.

TABLE 5 MIC of Example 1, Example 2, and Thymoquinone Against Multidrug Resistant Acinetobacter baumannii Isolates (μg/ml) Isolate 121 Isolate 127 Isolate 129 Example 1 16 ± 490.4 16 ± 490.4 16 ± 490.4 Example 2 1961.8 980.9 980.9 Thymoquinone 64 32 32

It is to be understood that a method for preventing, treating, or ameliorating microbial infections is not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter. 

1. A method for preventing, treating, or ameliorating infections caused by gram-negative bacteria, wherein the gram-negative bacteria is Acinetobacter baumannii, comprising administering a therapeutically effective amount of thymoquinone to a patient in need thereof.
 2. The method according to claim 1, wherein the thymoquinone is administered in a microemulsion.
 3. The method according to claim 2, wherein the microemulsion comprises thymoquinone, oil, a surfactant, and water.
 4. The method according to claim 3, wherein the oil is clove oil.
 5. The method according to claim 2, wherein the microemulsion is administered topically or systemically. 6-16. (canceled) 